WASHINGTON – The often bitter rhetoric surrounding the Senate’s Obamacare debate has not only exposed fissures within the Republican caucus but sparked talk about serious Tea Party challenges for some veteran lawmakers held in conservative disfavor.

Senate Republican Leader Mitch McConnell, of Kentucky, and Sen. Lindsey Graham (R-S.C.), who riled the party’s right wing by refusing to embrace efforts to filibuster a House-passed spending bill that defunded the Affordable Care Act – thus affording Senate Democratic Leader Harry Reid, of Nevada, an opportunity to delete the Obamacare language – are among those who may find themselves in the political cross-hairs.

Both McConnell and Graham have drawn Tea Party challenges: Matt Bevin a Louisville businessman, is taking on McConnell while Nancy Mace, a Charleston businesswoman and the first female graduate of The Citadel, is opposing Graham. Both are looking to use the Obamacare debate to their advantage in the 2014 GOP primary.

They are not alone. Senate Republican Whip John Cornyn, of Texas, who backed McConnell’s play and crossed swords with Sen. Ted Cruz (R-Texas), a leader in the filibuster effort, has yet to draw any 2014 opposition. But there is some discussion that Rep. Louie Gohmert (R-Texas), a Tea Party darling who remained in the Senate chamber throughout much of Cruz’s recent anti-Obamacare talk-a-thon, may jump in.

McConnell and Cornyn appear to be drawing most of the conservative bile for failing to work sufficiently hard to rally support to kill the healthcare law. The Senate Conservatives Fund, a political action committee “dedicated to electing strong conservatives to the United States Senate,” founded by former Sen. Jim DeMint, a South Carolina Republican, charged that the pair’s refusal to support Cruz’s efforts amounted to the “ultimate betrayal.”

DeMint, who tussled with McConnell from the right during his tenure on Capitol Hill, left the upper chamber earlier this year to head the Heritage Foundation but the organization he left still has influence with the right wing – and money to sink into campaigns.

“Mitch McConnell and John Cornyn have surrendered to Barack Obama, Harry Reid, and the Democrats,” the group said in a missive to supporters. “More importantly, they have surrendered to Obamacare — the biggest job killer in America.”

The Fund has unveiled plans to run a 60-second commercial in Kentucky markets this week attacking McConnell, although it has yet to make an endorsement in the race. The ad states that “Republicans in Congress can stop Obamacare by refusing to fund it, but Senator Mitch McConnell refuses to lead the fight.”

Meanwhile, the Madison Project, another outfit that raises money for conservative candidates, run by former congressman Jim Ryun, has launched a web ad that features a figure with McConnell’s face attached to the cartoon body of a chicken.

“During every election cycle Senator McConnell eagerly touts his supposed ‘power’ and ‘clout’ as the Republican Senate leader,” said Drew Ryun of the Madison Project. “Ironically, he appears to be too chicken to use this power to take a definitive stance on any important issue until the debate is already resolved or the outcome is a forgone conclusion. As Senate GOP Leader, McConnell acts more like a bystander or a follower until he figures out the most politically advantageous stance to best preserve his personal power.”

McConnell announced he would not join Cruz in his effort to block the House-passed spending and Obamacare measure from coming to a final vote because it includes language to eliminate funding and could result in a governmental shutdown if not adopted by Sept. 30, the end of the federal fiscal year.

The Republican leader said he plans to oppose Reid’s effort to strip the defunding provision from the bill. But Bevin countered that McConnell is turning his back on the conservative war against Obamacare.

“Like so many other crucial fights, Mitch McConnell has caved to Harry Reid on Obamacare and is refusing to fight to defund this disastrous legislation,” Bevin said.